Diagnostic apparatus

Abstract

A diagnostic apparatus capable of reliably detecting a ground short of a linear solenoid valve and a drive circuit thereof is provided. A diagnostic apparatus 10 in which a drive circuit 2 is configured of switching means 3 for supplying an electric current to a linear solenoid valve 1 and variably regulating a valve opening degree on the basis of inputted ON-OFF signals, current detection means 4 for detecting an electric current flowing from the switching means 3 to the linear solenoid valve 1, and control means 5 for outputting ON-OFF signals to the switching means 3 on the basis of a detected current value from the current detection means 4 so that the linear solenoid valve has a target opening degree, and which diagnoses a ground short between the drive circuit 2 and the linear solenoid valve 1, the diagnostic apparatus including ground short detection means 5 for detecting a switching of ON-OFF signals inputted in the switching means 3 and determining a ground short fault when the number of ON-OFF switching cycles per a predetermined interval is equal to or less than a predetermined number of cycles.

Dependencies are inferred from the claim text.